In March, Doncaster's children's services department was taken over by a senior management team appointed by the children's secretary, Ed Balls, who acted after his own department found serious failings in child protection.

Then, the following month, came news of the attack on a pair of young boys in the village of Edlington, on the edge of Doncaster.

The perpetrators were also children, then aged 11 and 10, who were at the time on the council's child protection register and had been living with foster parents.

The questions began immediately, and have only become more pressing since it emerged that not only were the boys well known to police for acts of violence but, on the morning they carried out the attack, they were meant to have been at a police station for questioning over a separate assault.

Critics questioned why the brothers were not in a more secure form of care, in which they could not roam free.

Doncaster council said today an investigation was already taking place. "A serious case review is under way by the Doncaster safeguarding children board to establish if there are lessons to be learned by any agency involved."

The council had already launched similar case reviews into the deaths of seven children in the area during a five-year period. Two of them were murdered by their fathers. Four were less than a year old.

Reviews into three of the deaths have been published so far, and all were youngsters who had been abused or neglected before their death.

In each of the cases it was found that social workers missed chances to intervene.

The most notorious case, that of Amy Howson, had echoes of the abuse suffered by Baby Peter, but attracted much less attention. Amy, aged 16 months, was already malnourished when her father killed her in December 2007. Her father, then 25, was jailed for life for murder last year. Amy's mother was jailed for child cruelty.

Late last year, Ofsted was highly critical of children's services in Doncaster, labelling them among the worst in the country.

Balls said he was "particularly concerned" about the quality of help for children in the town.

Local anger over such concerns led the town's independent mayor, Martin Winter, to opt against standing for re-election in May this year.

Few details have been released about social services' involvement with the two young defendants and their family. Court hearings have been told both boys were on the child protection register and both had been expelled from school.

At the time of the attack, both boys had been placed in foster care in the Edlington area. They had only been there since 10 March, about three weeks before the attack.

People living close to the family home said they appealed to the council and police for help to deal with the problems the family were causing. And a friend of the boys' mother said she had pleaded with social workers for help controlling her sons.